Feasibility study of energy storage options for photovoltaic electricity generation in detached houses in Nordic climates

Energy storage is an emerging solution to mitigate the intermittency of solar photovoltaic (PV) power generation and includes several technologies that could also be applied in small-scale residential applications. However, energy storage systems have not yet seen wide-scale integration into the energy systems of buildings, due to the inherently high investment costs of energy storages. Nevertheless, as new EU policies suggest stricter climate targets for 2030, including proposals to increase the share of renewable energy in the building sector to 49 %, a potential widescale integration of solar PV systems combined with various energy storage technologies in many types of buildings could follow. Subsequently, this paper models the use of lithium-ion battery storage (LIB), hydrogen storage, and thermal energy storage (TES) in detached houses in southern Finland, in order to evaluate the cost-effectiveness of utilizing energy storages to enhance residential photovoltaic electricity generation.

This study found that solar PV systems without selling surplus electricity to the grid were profitable up to a renewable fraction of 10 % with 2019 market prices and up to 35 % with the 2021 unusually high market prices. The possibility of selling the surplus electricity to the grid improves the profitability further, up to a renewable fraction of 20 % with 2019 market prices and up to 50 % with 2021 market prices. Out of the examined energy storage technologies, LIB storage turned out to be the most financially feasible storage option with costs relatively close to stand-alone solar PV systems in many scenarios, whereas utilizing either hydrogen storage or TES and HP in combination with solar PV systems turned out to be multiple times more expensive than using grid electricity to power detached houses. Consequently, this paper found that integrating energy storage systems with photovoltaic power generation in individual detached houses would require either sustained high electricity market prices or subsidies to be economically viable in the Nordic climate.